Research For The Reasonable Height Of The City Road Of Song Bei Area In Harbin City

Song Bei planning area is a new established scoping in Harbin that approved by the State Council. The area are constructed cosmically at present, in road constructing process, elevation 117.50m is used as control all the while, but ground elevation in this area is between 115.00~118.00m generally,so the 117.50m result in the problem of high roadbed during the process of construction.In the process of researching the reasonable height of the cityroad in Song Bei area, carry through field investigation of hydrogeology condition firstly, and choose representative constructed roads as research object in according to the present situation of road construction and natural characteristic, collect subgrade soil. And then combine with laboratory test, it was studied engineering properties of subgrade soils, but also mainly studied the effect of water content on mechanical properties of subgrade soils. The results showed that when the water content in the cohesive soil subgrade be controlled under the optimum water content, the strength(CBR) of subgrade filler is 6.6%, and the bearing capacity is 36.6MPa, can satisfied the pavement demand to subgrad strength, but the strength decreased with the increasing of water content. The result of freezing and thawing test showed that viscous subgrade soil effect of the variation of water temperature conditions, freeze-thaw cycles fuction effected on water content,density,springback modulus,shearing strength. Make use of SPSS statistical analysis software to build dry and humidity conditions model of subgrade gradually, and prove the availability model significative by means a series of hypothesis testings. Establish the critical height of the cohesive soil subgrade that suitable for the natural conditions of Song Bei area by making use of the model, the critical height at dry state is 2.5m, at medium moist state is 2.2m and at damp state is 1.9m calculated by the model. The research result provides road planning design of Song Bei area with theoretical reference, and has active guiding significance for the construction of road engineering.